Project description:Repressor element-1 silencing transcription factor (REST) is required for mature neurons formation. REST dysregulation underlies a key mechanism of neurodegeneration associated with neurological disorders. However, the mechanisms leading to alterations of REST-mediated silencing of key neurogenesis genes are not known. Here we show that BRAT1, a gene linked to neurodegenerative diseases, is required for activation of REST-responsive genes during neuronal-differentiation. We find that INTS11 and INTS9 subunits of Integrator complex interact with BRAT1 as a distinct trimeric complex to activate critical neuronal genes during differentiation. BRAT1 depletion results in persistence of REST residence on critical neuronal genes disrupting the differentiation of NT2 cells into astrocytes and neural cells. We identified BRAT1 and INTS11 co-occupying the promoter region of these genes and pinpoint a role for BRAT1 in recruiting INTS11 to their promoters. Disease-causing mutations in BRAT1 diminish its association with INTS11/INTS9, linking the manifestation of disease phenotypes with a defect in transcriptional activation of key neuronal genes by BRAT1/INTS11/INTS9 complex.
Project description:The study focuses on an extensive biochemical fractionation with in-depth quantitative mass spectrometric profiling in the mitochondrial (mt) extracts of cultured human NTera2 embryonal carcinoma stem cells (i.e. ECSCs or undifferentiated state) and upon exposure to retinoic acid-induced differentiated neurons (DNs) to establish a network of high-quality mt protein-protein interactions. The resulting network showed that most of the native mt protein complexes with predicted subunits are previously unreported and endured extensive changes during neuronal differentiation and influence neuronal function and neurodegenerative disorder attributes.
Project description:The study focuses on an extensive biochemical fractionation with in-depth quantitative mass spectrometric profiling in the mitochondrial (mt) extracts of cultured human NTera2 embryonal carcinoma stem cells (i.e. ECSCs or undifferentiated state) and upon exposure to retinoic acid-induced differentiated neurons (DNs) to establish a network of high-quality mt protein-protein interactions. The resulting network showed that most of the native mt protein complexes with predicted subunits are previously unreported and endured extensive changes during neuronal differentiation and influence neuronal function and neurodegenerative disorder attributes.
Project description:The study focuses on an extensive biochemical fractionation with in-depth quantitative mass spectrometric profiling in the mitochondrial (mt) extracts of cultured human NTera2 embryonal carcinoma stem cells (i.e. ECSCs or undifferentiated state) and upon exposure to retinoic acid-induced differentiated neurons (DNs) to establish a network of high-quality mt protein-protein interactions. The resulting network showed that most of the native mt protein complexes with predicted subunits are previously unreported and endured extensive changes during neuronal differentiation and influence neuronal function and neurodegenerative disorder attributes.
Project description:The study focuses on an extensive biochemical fractionation with in-depth quantitative mass spectrometric profiling in the mitochondrial (mt) extracts of cultured human NTera2 embryonal carcinoma stem cells (i.e. ECSCs or undifferentiated state) and upon exposure to retinoic acid-induced differentiated neurons (DNs) to establish a network of high-quality mt protein-protein interactions. The resulting network showed that most of the native mt protein complexes with predicted subunits are previously unreported and endured extensive changes during neuronal differentiation and influence neuronal function and neurodegenerative disorder attributes.
Project description:During sensitive postnatal periods, brain neural circuits undergo significant refinement coincident with widespread neuronal alternative splicing events in which hundreds of genes alter their splice site selection to generate isoforms essential for synaptic plasticity. Here, we reveal that neuronal activity-dependent serine119 phosphorylation of paxillin (p-paxillin S119) acts as a molecular switch in the nucleus to modulate alternative splicing during this period. We report that following NMDA receptor activation, nuclear p-paxillin S119 is recruited to nuclear speckles, where it interacts with U2AFs and splicing factors. Neuronal paxillin expression is required for timely alternative splicing of synaptic factors, including Snap25. Consequently, young mice lacking paxillin S119 phosphorylation exhibit significantly reduced levels of Snap25-5b isoforms, impaired presynaptic function at hippocampal Schaffer collateral-CA1 synapses, and deficits in short-term learning and memory. These findings support the idea that nuclear p-paxillin S119 is a critical mediator of alternative splicing programs in postnatal neurons during a sensitive period essential for neural plasticity.
Project description:RNA binding proteins play an important role in regulating alternative pre-mRNA splicing and in turn cellular gene expression. Polypyrimidine tract binding proteins, PTBP1 and PTBP2, are paralogous RNA binding proteins that play a critical role in the process of neuronal differentiation and maturation; changes in the concentration of PTBP proteins during neuronal development direct splicing changes in many transcripts that code for proteins critical for neuronal differentiation. How the two related proteins regulate different sets of neuronal exons is unclear. The distinct splicing activities of PTBP1 and PTBP2 can be recapitulated in an in vitro splicing system with the differentially regulated N1 exon of the c-src pre-mRNA. Here, we conducted experiments under these in vitro splicing conditions to identify PTBP1 and PTBP2 interacting partner proteins.
Project description:Alternative RNA splicing is an essential and dynamic process in neuronal differentiation and synapse maturation, and dysregulation of this process has been associated with neurodegenerative diseases. Recent studies have revealed the importance of RNA-binding proteins in the regulation of neuronal splicing programs. However, the molecular mechanisms involved in the control of these splicing regulators are still unclear. Here we show that KIS, a kinase upregulated in the developmental brain, imposes a genome-wide alteration in exon usage during neuronal differentiation. KIS contains a protein-recognition domain common to spliceosomal components and phosphorylates PTBP2, counteracting the role of this splicing factor in exon exclusion. At the molecular level, phosphorylation of unstructured domains within PTBP2 causes its dissociation from two co-regulators, Matrin3 and hnRNPM, and hinders the RNA-binding capability of the complex. Furthermore, KIS and PTBP2 display strong and opposing functional interactions in synaptic spine emergence and maturation. Taken together, our data uncover a post-translational control of splicing regulators that link transcriptional and alternative exon usage programs in neuronal development.
Project description:Both microRNAs and alternative pre-mRNA splicing have been implicated in the development of the nervous system (NS), but functional interactions between these two pathways are poorly understood. We demonstrate that the neuron-specific microRNA miR-124a directly targets PTBP1/PTB/hnRNPI mRNA, which encodes a global repressor of alternative pre-mRNA splicing in non-neuronal cells. Among the targets of PTBP1 is a critical cassette exon in the pre-mRNA of PTBP2/nPTB/brPTB, an NS-enriched PTBP1 homolog. When this exon is skipped, PTBP2 mRNA is subject to nonsense-mediated decay. During neuronal differentiation, miR-124a reduces PTBP1 levels leading to the accumulation of correctly spliced PTBP2 mRNA and a dramatic increase in PTBP2 protein. These events culminate in the transition from non-NS to NS-specific alternative splicing patterns. We also present evidence that miR-124a plays a key role in the differentiation of progenitor cells to mature neurons. Thus, miR-124a promotes NS development at least in part by regulating an intricate network of NS-specific alternative splicing. We used microarrays to detail the global programme of gene expression of CAD cells over-expressing miR-124a-2. Experiment Overall Design: Expression data from CAD cells transfected with plasmid expressing miR-124a-2.